Valance Units

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What is a 'valance unit' system?



Eric Youngson's picture
Joined: 2011-09-30
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I don't know if the induction unit with the 2-pipe option would be
appropriate for this, but it might be worth checking out. Personally I
haven't tried it yet, but it seems to be the most appropriate.


A valance unit is essentially an induction unit. From Harvard's website

Valance systems are induction units that provide cooling or heating. In
cooling mode, chilled water is circulated through finned coils in the
unit. As warm air rises, it passes over the coils, is cooled, and sinks
to the floor, creating a constant convective loop. By eliminating the
need for forced air, the cooling load is reduced. In heating mode, hot
water passes through the finned tubes. As air passes over the coils, a
layer of radiative warmth is formed across the ceiling and is radiated
back down into the space. These units eliminate the need for an
electric-driven fan to push air, saving money and energy, while reducing
draft and eliminating noise.

Vikram Sami, LEED AP

Vikram Sami's picture
Joined: 2011-09-30
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We've modeled several valance systems. Valance units are sometimes called
"passive chilled beams". They basically consist of a piece of fin-tube,
which is used for both heating and cooling, along with a drain pan to catch
condensate drips. While active chilled beams have an air supply, and could
be modeled as induction units, these do not have an air supply attached.
Typically, ventilation air is supplied through a separate dedicated outdoor
air system.

The easiest way to think of these is like a fan coil unit without the fan,
and that is exactly how we model them. In eQuest, set the system type to fan
coil, with chilled water and hot water coils, set the unit fan energy to
zero. One thing to watch for - valance units typically run at a low
waterside delta T (6 deg F on the cooling side) - make sure you've
accounted for that or your pump energy will be too low.

We've found that for certain applications (like dormitories) valance systems
provide a high efficiency, low cost alternative, well worth considering.


Christopher Schaffner, PE, LEEDR AP

Christopher Schaffner's picture
Joined: 2011-09-30
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